Bump next from 15.5.4 to 15.5.6 (#312)

Bumps [next](https://github.com/vercel/next.js) from 15.5.4 to 15.5.6.
- [Release notes](https://github.com/vercel/next.js/releases)
- [Changelog](https://github.com/vercel/next.js/blob/canary/release.js)
- [Commits](vercel/next.js@v15.5.4...v15.5.6)

---
updated-dependencies:
- dependency-name: next
  dependency-version: 15.5.6
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

package-lock.json

@@ -11,7 +11,7 @@
   },
   "dependencies": {
     "firebase": "^12.2.1",
-    "next": "^15.5.4",
+    "next": "^15.5.6",
     "react": "19.2.0",
     "react-dom": "19.2.0"
   },